[Show abstract][Hide abstract] ABSTRACT: CaMKII was suggested to mediate ischemic myocardial injury and adverse cardiac remodeling. Here, we investigated the roles of different CaMKII isoforms and splice variants in ischemia/reperfusion (I/R) injury by the use of new genetic CaMKII mouse models. Although CaMKIIδC was upregulated 1 day after I/R injury, cardiac damage 1 day after I/R was neither affected in CaMKIIδ-deficient mice, CaMKIIδ-deficient mice in which the splice variants CaMKIIδB and C were re-expressed, nor in cardiomyocyte-specific CaMKIIδ/γ double knockout mice (DKO). In contrast, 5 weeks after I/R, DKO mice were protected against extensive scar formation and cardiac dysfunction, which was associated with reduced leukocyte infiltration and attenuated expression of members of the chemokine (C-C motif) ligand family, in particular CCL3 (macrophage inflammatory protein-1α, MIP-1α). Intriguingly, CaMKII was sufficient and required to induce CCL3 expression in isolated cardiomyocytes, indicating a cardiomyocyte autonomous effect. We propose that CaMKII-dependent chemoattractant signaling explains the effects on post-I/R remodeling. Taken together, we demonstrate that CaMKII is not critically involved in acute I/R-induced damage but in the process of post-infarct remodeling and inflammatory processes.
EMBO Molecular Medicine 09/2014; 6(10). DOI:10.15252/emmm.201403848 · 8.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Advanced glycation end products (AGEs), S100/calgranulins, high-mobility group box (HMGB)1-protein, amyloid β-peptides, and the family of β-sheet fibrils have been shown to contribute to a number of chronic diseases such as diabetes, amyloidosis, and cancer by promoting cellular dysfunction via binding to the receptor for advanced glycation end products (RAGE). Engagement of RAGE leads to the activation of the nuclear factor (NF)-κB superfamily of transcription factors, which have been implicated in the regulation of numerous cellular processes such as cell survival, apoptosis, and secretion of cytokines in many cell types in immune cells but also cardiomyocytes, endothelial cells, and fibroblasts. However, sustained activation of NF-κB seems to be detrimental and promotes the development of heart failure by eliciting signals that trigger chronic inflammation through enhanced elaboration of various cytokines including tumour necrosis factor α (TNF-α), interleukin-1 (IL-1), and interleukin 6 (IL-6). Furthermore, engagement of RAGE appears to lead to prolonged NF-κB-mediated activation overwhelming endogenous autoregulatory feedback inhibition loops. The underlying mechanisms that account for the multifaceted and differential effects of NF-κB on cardiac cells are presently not fully understood. In this review, we will focus on the role of RAGE as a master switch of inflammation by converting a brief pulse of cellular activation to sustained cellular dysfunction. Furthermore, we discuss how duration of activation and cellular context may explain mechanistically the differential effects of NF-κB signaling in the heart.
Forum on immunopathological diseases and therapeutics 01/2013; 4(2):133-147. DOI:10.1615/ForumImmunDisTher.2013008768
[Show abstract][Hide abstract] ABSTRACT: The role of inflammation in atherosclerosis is widely appreciated. High mobility group box 1 (HMGB1), an injury-associated molecular pattern molecule acting as a mediator of inflammation, has recently been implicated in the development of atherosclerosis. In this study, we sought to investigate the association of plasma HMGB1 with coronary plaque composition in patients with suspected or known coronary artery disease (CAD).
HMGB1, high sensitive troponin T (hsTnT) and high sensitive C-reactive protein (hsCRP) were determined in 152 consecutive patients with suspected or known stable CAD who underwent clinically indicated 256-slice coronary computed tomography angiography (CCTA). Using CCTA, we assessed 1) coronary calcification, 2) non-calcified plaque burden and 3) the presence of vascular remodeling in areas of non-calcified plaques.
Using univariate analysis, hsCRP, hsTnT and HMGB1 as well as age, and atherogenic risk factors were associated with non-calcified plaque burden (r = 0.21, p = 0.009; r = 0.48, p<0.001 and r = 0.34, p<0.001, respectively). By multivariate analysis, hsTnT and HMGB1 remained independent predictors of the non-calcified plaque burden (r = 0.48, p<0.01 and r = 0.34, p<0.001, respectively), whereas a non-significant trend was noticed for hs-CRP (r = 0.21, p = 0.07). By combining hsTnT and HMGB1, a high positive predictive value for the presence of non-calcified and remodeled plaque (96% and 77%, respectively) was noted in patients within the upper tertiles for both biomarkers, which surpassed the positive predictive value of each marker separately.
In addition to hs-TnT, a well-established cardiovascular risk marker, HMGB1 is independently associated with non-calcified plaque burden in patients with stable CAD, while the predictive value of hs-CRP is lower. Complementary value was observed for hs-TnT and HMGB1 for the prediction of complex coronary plaque.
PLoS ONE 12/2012; 7(12):e52081. DOI:10.1371/journal.pone.0052081 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The extracellular heterodimeric protein S100A8/A9 activates the innate immune system through activation of the receptor of advanced glycation end products (RAGE) and Toll-like receptors. As activation of RAGE has recently been associated with sustained myocardial inflammation and heart failure (HF) we studied the role of S100A8/A9 in the development of post-ischemic HF. Hypoxia led to sustained induction of S100A8/A9 accompanied by increased nuclear factor (NF-)κB binding activity and increased expression of pro-inflammatory cytokines in cardiac fibroblasts and macrophages. Knockdown of either S100A8/A9 or RAGE rescued the induction of pro-inflammatory cytokines and NF-κB activation after hypoxia. In a murine model of post-ischemic HF both cardiac RNA and protein levels of S100A8/A9 were elevated as soon as 30 min after hypoxia with sustained activation up to 28 days after ischemic injury. Treatment with recombinant S100A8/A9 resulted in reduced cardiac performance following ischemia/reperfusion. Chimera experiments after bone marrow transplantation demonstrated the importance of RAGE expression on immune cells for their recruitment to the injured myocardium aggravating post-ischemic heart failure. Signaling studies in isolated ventricles indicated that MAP kinases JNK, ERK1/2 as well as NF-κB mediate signals downstream of S100A8/A9-RAGE in post-ischemic heart failure. Interestingly, cardiac performance was not affected by administration of S100A8/A9 in RAGE(-/-)-mice, which demonstrated significantly improved cardiac recovery compared to WT-mice. Our study provides evidence that sustained activation of S100A8/A9 critically contributes to the development of post-ischemic HF driving the progressive course of HF through activation of RAGE.
Archiv für Kreislaufforschung 03/2012; 107(2):250. DOI:10.1007/s00395-012-0250-z · 5.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: High-Mobility-Group Box 1 (HMGB1) has been established as an important mediator of myocardial inflammation and associated with progression of heart failure (HF). The aim of this study was to analyze the prognostic value of systemic HMGB1 levels in HF patients with ischemic and non-ischemic cardiomyopathy.
We conducted an analysis (median follow-up time 2.5 years) of HMGB1 plasma concentration in 154 patients with systolic HF and correlated the results with disease severity and prognosis. HMGB1 in HF patients with severe symptoms (NYHA III/IV; 5.35 ng/ml; interquartile range (IQR) = 3.48-8.42 ng/ml) was significantly elevated compared with that in patients with mild symptoms (NYHA I/II; 3.37 ng/ml, IQR = 2.31-5.22 ng/ml, p < 0.0001) and with controls (3.25 ng/ml, IQR = 3.04-3.67 ng/ml, p < 0.0001). HMGB1 levels correlated with other markers of heart failure indicating an association of HMGB1 with disease severity in HF. In a univariate cox regression model for the combined endpoint of death and heart transplantation, HMGB1 proved to be a predictor at cut-off values based on HMGB1 terciles of either 3.4 or 6.1 ng/ml (p = 0.001 and p < 0.0001, respectively). In a multivariate cox regression model, which included NT-proBNP, creatinine, age, NYHA class, white blood cell count, anemia, and age, HMGB1 remained an independent predictor of the combined endpoint (hazard ratio (HR) = 2.48, 95% confidence interval (CI) = 1.06-5.83, p = 0.037 and HR = 2.48, 95% CI = 1.31-4.71, p = 0.005, respectively).
Our findings demonstrate that HMGB1 plasma concentration is elevated in HF and correlates with disease severity and that is an independent predictor of the combined endpoint death and heart transplantation in HF patients.
Clinical Research in Cardiology 01/2012; 101(6):427-35. DOI:10.1007/s00392-011-0409-x · 4.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Autoimmunity against cardiac troponin I (cTnI) has deleterious effects on the infarcted myocardium early after onset of ischaemia. Here, we explored the impact of cTnI-autoimmunity in the long term. Furthermore, we studied the effects of cTnI-autoimmunity on the infarcted myocardium following revascularization measures in terms of ischaemia reperfusion injury (IRI), which resembles clinical reality more closely.
After immunization with either cTnI (n= 10) or a control buffer (n= 14), A/J mice underwent chronic coronary artery ligation. Another group of mice immunized with cTnI (n= 13) underwent temporary coronary artery occlusion and were compared with non-immunized controls (n= 17). Left ventricular function was evaluated by echocardiography. Hearts were obtained for histological evaluation. Immunological responses were quantified by analysis of cytokine and chemokine patterns as well as anti-cTnI antibody titres. Myocardial inflammation and cardiac dysfunction were detectable as late as 180 days after myocardial infarction (MI). Previous cTnI-immunization enhanced myocardial inflammation and dysfunction. Mice subjected to cTnI-immunization before IRI exhibited a higher inflammation score, an upregulated expression of pro-inflammatory chemokines (IP-10, MIP-1, Ltn, RANTES, TCA-3) and chemokine receptors (CCR2, CCR5), increased interleukin (IL)-2, interferon (IFN)-g, and decreased IL-10 production along with a markedly reduced fractional shortening after IRI compared with the controls.
Our results demonstrate for the first time that cTnI-induced autoimmune response not only leads to increased myocardial inflammation and impaired cardiac function 180 days after chronic coronary artery ligation, but also exacerbates ischaemia/reperfusion injury compared with non-immunized controls. Hence, the presence of cTnI-autoimmunity could render subjects more vulnerable to prospective myocardial injury, be it MI, or secondary revascularization measures.
European Journal of Heart Failure 08/2011; 13(10):1052-9. DOI:10.1093/eurjhf/hfr098 · 6.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Antigen-specific therapy is a compelling approach for the treatment of autoimmune conditions. Primary goal is to induce the specific tolerization of self-reactive immune cells without altering host immunity against pathogens. We studied the effects of mucosal tolerance induction on cTnI-induced experimental autoimmune myocarditis (EAM) and post-infarct remodeling. METHODS: Mucosal tolerance was induced by intranasal application of cTnI, alternatively anti-CD3 p.o. Protocols varied in frequency, dosage and time point of application before EAM. We then applied the most effective regimen to mice undergoing myocardial infarction in order to verify its effectiveness in post-infarct cardiac remodeling. The myocardium was evaluated on histological slides and for the cytokine secretion pattern, while echocardiography determined cardiac function. RESULTS: A single dose of 100μg of cTnI 7days prior to myocarditis appeared to be most effective in suppressing inflammation and fibrosis (p=0.03), while improving fractional shortening (p=0.02). Treatment with intranasal cTnI upregulated IL-10 expression. On the other hand, frequent intranasal application of high doses of cTnI increased myocardial inflammation. Anti-CD3 p.o. showed the propensity to reduce myocardial inflammation and improve cardiac function. The single dose regimen of i.n. cTnI applied 7days before a myocardial infarction reduced inflammation by trend (p=0.07) and improved heart function (p=0.002). Moreover, expression of matrix metalloproteinases 9 and 14 significantly decreased when treated with intranasal cTnI (p<0.01). CONCLUSIONS: Depending on the optimal amount, the time period and the choice of antigen, effective mucosal tolerance can be achieved and represents an appealing therapeutic approach in the inflammatory process of cardiac remodeling.
International journal of cardiology 06/2011; 162(3). DOI:10.1016/j.ijcard.2011.05.057 · 4.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: High-mobility group box 1 (HMGB1) protein is an innate danger signal for the initiation of host defence and tissue repair. The aim of this study was to analyse serum HMGB1 concentration and its correlation with infarct transmurality and functional recovery in patients with ST-elevation (STEMI) and non-ST-elevation myocardial infarction (NSTEMI).
We prospectively examined patients with first-time STEMI (n = 46) or NSTEMI (n = 49), treated according to current guidelines. Contrast-enhanced cardiac magnetic resonance imaging was performed 2-4 days after infarction for the estimation of infarct transmurality and was repeated after 6 months for the estimation of residual left ventricular function. HMGB1 was measured 2-4 days after infarction.
High-mobility group box 1 concentration was related to infarct size and to residual ejection fraction in patients with STEMI (r(2) = 0.81 and r(2) =0.40, respectively, P < 0.001 for both) and NSTEMI (r(2) = 0.74 and r(2) = 0.25, respectively, P < 0.001 for both). Receiver operating characteristic (ROC) curve-derived cut-off values of 6.2 and 5.9 ng mL(-1) for patients with STEMI and NSTEMI, respectively, were predictive of infarct transmurality greater than 75% (STEMI: area under the curve (AUC) = 0.93, standard error (SE) = 0.04, 95% confidence interval (CI) = 0.81-0.98; NSTEMI: AUC = 0.96, SE = 0.04, 95% CI = 0.86-0.99). HMGB1 cut-off values of 7.2 and 6.4 ng mL(-1) for patients with STEMI and NSTEMI, respectively, were predictive of residual ejection fraction 6 months after myocardial infarction (MI) (STEMI: AUC = 0.81, SE = 0.07, 95% CI = 0.66-0.91; NSTEMI: AUC = 0.81, SE = 0.09, 95% CI = 0.68-0.91).
High-mobility group box 1 serum levels represent a highly valuable surrogate marker for infarct transmurality and for the prediction of residual left ventricular function after MI.
Journal of Internal Medicine 03/2011; 270(3):245-53. DOI:10.1111/j.1365-2796.2011.02369.x · 6.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Peripheral artery disease (PAD) is associated with high cardiovascular mortality and a poor quality of life. The AT1-receptor blocker telmisartan has been shown to have pleiotropic effects and it may also improve endothelial function. The aim of this study was to analyze the effects of telmisartan on absolute walking distance (WD) and endothelial function in patients with PAD.
In a single centre, single-blinded, prospective study, 36 patients with PAD at stage Fontaine II or higher and mild to moderate arterial hypertension were treated with telmisartan 40/80 mg once daily or placebo for 12 months. Primary endpoint was the improvement of the absolute treadmill WD. Flow-mediated vasodilation (FMD), carotid intima-media thickness (IMT), ankle-brachial index (ABI) and disease-related quality of life (DRQL) were examined as well.
After 12 months, maximum WD increased by 26% in the telmisartan group (P < 0.001). However, in the placebo group it was comparable to baseline. FMD rose by 40% in the telmisartan group while it deteriorated in the placebo group (P < 0.001). IMT and ABI were comparable in both groups at baseline and did not change considerably after 12 months. In non-diabetic patients (72.2%), the ABI did not change in the placebo group, whereas it increased by 11% in the telmisartan group (P < 0.001). While the DRQL remained stable in the telmisartan group, placebo treatment was associated with a marked deterioration (P < 0.01).
Telmisartan improves WD and endothelial function, the ABI in non-diabetic patients and it may prevent further loss of quality of life in patients with advanced PAD.
Clinical Research in Cardiology 12/2010; 99(12):787-94. DOI:10.1007/s00392-010-0184-0 · 4.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Diabetes mellitus (DM) is a major independent risk factor for cardiovascular disease, but also leads to cardiomyopathy. However, the etiology of the cardiac disease is unknown. Therefore, the aim of this study was to identify molecular mechanisms underlying diabetic heart disease. High glucose treatment of isolated cardiac fibroblasts, macrophages and cardiomyocytes led to a sustained induction of HMGB1 on the RNA and protein level followed by increased NF-κB binding activity with consecutively sustained TNF-α and IL-6 expression. Short interference (si) RNA knock-down for HMGB1 and RAGE in vitro confirmed the importance of this axis in diabetes-driven chronic inflammation. In a murine model of post-myocardial infarction remodeling in type 1 diabetes, cardiac HMGB1 expression was significantly elevated both on RNA and protein level paralleled by increased expression of pro-inflammatory cytokines up to 10 weeks. HMGB1-specific blockage via box A treatment significantly reduced post-myocardial infarction remodeling and markers of tissue damage in vivo. The protective effects of box A indicated an involvement of the mitogen-activated protein-kinases jun N-terminal kinase and extracellular signal-regulated kinase 1/2, as well as the transcription factor nuclear factor-kappaB. Interestingly, remodeling and tissue damage were not affected by administration of box A in RAGE(-/-) mice. In conclusion, HMGB1 plays a major role in DM and post-I/R remodeling by binding to RAGE, resulting in activation of sustained pro-inflammatory pathways and enhanced myocardial injury. Therefore, blockage of HMGB1 might represent a therapeutic strategy to reduce post-ischemic remodeling in DM.
Archiv für Kreislaufforschung 11/2010; 105(6):805-20. DOI:10.1007/s00395-010-0114-3 · 5.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Heart failure is an increasingly prevalent disorder with considerable morbidity and mortality. Although many causal mechanisms such as inherited cardiomyopathies, ischemic cardiomyopathy, or muscular overload are easily identified in clinical practice, the events that determine the progression of cardiac injury to heart failure and adverse ventricular remodeling are still unclear. Yet there is compelling evidence that inflammatory mechanisms contribute to the progression of heart failure. High-mobility group box-1 (HMGB1) is a newly recognized potent innate "danger signal" that is released by necrotic cells and by activated immune cells. HMGB1 signals via the receptor for advanced glycation end-product (RAGE) and members of the toll-like receptor (TLR) family. We have demonstrated an important role for HMGB1 and RAGE in the pathogenesis of early- and late-phase complications following ischemia/reperfusion (I/R) injury of the heart. In addition, enhanced postmyocardial infarction remodeling in type 1 diabetes mellitus was partially mediated by HMGB1 activation. We propose that the interaction of HMGB1 and RAGE is a key component initiating and sustaining the inflammatory response in inflammatory cardiomyopathy eventually leading to heart failure. Thus HMGB1-antagonizing gene therapy represents a new therapeutic strategy.
Seminars in Thrombosis and Hemostasis 03/2010; 36(2):185-94. DOI:10.1055/s-0030-1251503 · 3.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transient left ventricular (LV) ballooning syndrome, or Takotsubo syndrome, is characterized by a reversible LV dysfunction. The pathophysiology has not been fully elucidated, but an excess of catecholamines seems to have an essential role. The case of a 27-year-old man who developed transient LV dysfunction resembling Takotsubo syndrome after self-injection of adrenaline is described. The present case may provide additional evidence to the hypothesis of excess sympathetic activation in LV ballooning syndrome.
The Canadian journal of cardiology 08/2009; 25(7):e261-2. DOI:10.1016/S0828-282X(09)70517-3 · 3.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In-stent restenosis of a previously atherosclerotic renal artery stenosis initially treated with endovascular stenting may
progress to subtotal occlusion and loss of renal function. The clinical course of an acute occlusion is mainly acute oligo-anuric
renal failure. Therefore, rapid diagnosis and treatment are critical for renal survival. Even after successful endovascular
treatment, a close clinical monitoring, and optimized medical treatment including sufficient blood pressure control, lipid
lowering and platelet inhibition, is mandatory to prolong the preservation of renal function. Here we present a patient with
subtotal in-stent stenosis affecting the left solitary kidney and recovery of renal function 24 h after the revascularization
[Show abstract][Hide abstract] ABSTRACT: High-mobility group box-1 (HMGB1) is a nuclear factor released by necrotic cells and by activated immune cells. HMGB1 signals via members of the toll-like receptor family and the receptor for advanced glycation end products (RAGE). Although HMGB1 has been implicated in ischemia/reperfusion (I/R) injury of the liver and lung, its role in I/R injury of the heart remains unclear.
Here, we demonstrate that HMGB1 acts as an early mediator of inflammation and organ damage in I/R injury of the heart. HMGB1 levels were already elevated 30 minutes after hypoxia in vitro and in ischemic injury of the heart in vivo. Treatment of mice with recombinant HMGB1 worsened I/R injury, whereas treatment with HMGB1 box A significantly reduced infarct size and markers of tissue damage. In addition, HMGB1 inhibition with recombinant HMGB1 box A suggested an involvement of the mitogen-activated protein kinases jun N-terminal kinase and extracellular signal-regulated kinase 1/2, as well as the nuclear transcription factor nuclear factor-kappaB in I/R injury. Interestingly, infarct size and markers of tissue damage were not affected by administration of recombinant HMGB1 or HMGB1 antagonists in RAGE(-/-) mice, which demonstrated significantly reduced damage in reperfused hearts compared with wild-type mice. Coincubation studies using recombinant HMGB1 in vitro induced an inflammatory response in isolated macrophages from wild-type mice but not in macrophages from RAGE(-/-) mice.
HMGB1 plays a major role in the early event of I/R injury by binding to RAGE, resulting in the activation of proinflammatory pathways and enhanced myocardial injury. Therefore, blockage of HMGB1 might represent a novel therapeutic strategy in I/R injury.